Surgical router bits are used in certain surgical procedures to cut human or animal bones.
Conventional surgical router bits generally utilize either straight or spiral cutting flutes or grooves.
More particularly, and looking now at FIGS. 1 and 2, there is shown a conventional surgical router bit 2 of the sort having a plurality of straight cutting flutes or grooves 4. Typically four straight cutting flutes 4 are provided, although more or less than that number may be used. For the sake of example, four straight cutting flutes 4 are provided on the router bit shown in FIGS. 1 and 2. Each of the cutting flutes 4 defines a straight cutting edge 6 which, when the router bit is engaged with bone and the router bit is rotated in a counterclockwise direction (as seen from the angle of view of FIG. 2), will cut through the bone.
Looking next at FIGS. 3 and 4, there is shown a conventional surgical router bit 8 of the sort having a plurality of spiral cutting flutes or grooves 10. Typically two, three or four spiral cutting flutes 10 are provided, although more or less than that number may be used. For the sake of example, three spiral cutting flutes 10 are provided on the router bit 8 shown in FIGS. 3 and 4. Each of the cutting flutes 10 comprises a right hand cut, left hand spiral geometry defining a helical cutting edge 12 which, when the router bit is engaged with bone and the router bit is rotated in a counterclockwise direction (as seen from the angle of view of FIG. 4), will cut through the bone.
Conventional surgical router bits of the sort described above typically suffer from a number of disadvantages.
For one thing, such conventional surgical router bits tend to clog with bone debris as they cut through the bone.
For another thing, such conventional surgical router bits tend to subject the router bit to significant loads during cutting, with the result that the router bit can break or the bone can be damaged during cutting.
Furthermore, it has been found that with at least some prior art surgical router bits, the surgical router bit must be driven at the relatively high speed of 65,000 rpm in order to obtain acceptable cutting results. However, the use of such high rpm driving speeds is not preferred, inasmuch as almost all of the power units currently available in the field are adapted to run only at the relatively slow speed of 20,000 rpm. In addition, since the use of such high driving speeds can result in substantial heat being generated during cutting by virtue of the engagement of the router bit with the surrounding bone, and since this heat can actually burn the bone if the router bit should clog while the router bit is being driven at these higher speeds, the use of such high driving speeds is not preferred.